In the field of image display, video display devices represented by liquid crystal projectors are commonly used as means for easily obtaining a large-screen image at a low cost and often used mainly when a presentation is made while many people look at the same screen, such as conferences and press releases for products. In addition, digital signage (electronic sign board) is used to introduce products and promote stores.
Since the digital signage does not require embodied products such as posters and signboards, flexible display expressions are made possible in real time and at low cost. In one form thereof, there is a method of setting a display window or a window glass of a store as a screen and projecting by a projector from the front side of the screen, and this method is suitable for large-scale visual media. Using a reflective screen having both suitable transmissivity and suitable light diffusing properties as such a screen enables display of clear large-screen images and clear moving images while allowing the outside scenery to be seen through the screen.
Patent Literature 1 discloses a transmissive screen consisting of a substrate, a transparent thin film layer provided on the substrate, and a light-scatterer that is contained in the transparent thin film layer and has a median diameter of 0.01-1 μm, wherein the light-scatterer is diamond particulates obtained by subjecting a nanodiamond having a graphite phase obtained by detonation to oxidization treatment, and the transmissive screen has an excellent diffusive reflectivity without degradation of transmission visibility.
Patent literature 2 discloses a transmission projection screen prepared by stacking a metal thin film layer and a light diffusion layer on a thermoplastic resin film, wherein the light diffusion layer consists of a thermoplastic resin and light diffusion particles of 10-60 mass %, and the transmission projection screen is excellent in color clarity (high contrast effect) of a transmission projection image in a bright environment and in hot spot prevention. The metal thin film layer has a multi-layer structure consisting of 1) a low-refractive-index layer that consists of one or more selected from Au, Ag, Cu, Al and SiO2 and has a refractive index of 1.5 or less and 2) a high-refractive-index layer that consists of one or more selected from WO3, In2O3, ZrO2, ZnO, SnO2, and TiO2 and has a refractive index of 1.65 or greater, and the metal thin film layer has thermal insulation property by reflecting a heat ray. Note that, the transmission projection screen is used to project by a projector from the rear surface of the screen and different from the reflective screen used to project by a projector from the front surface of the screen.